#!/bin/bash
#########################################
#Function: add a new swap partition
#Usage: bash add_swap.sh
#Author: Customer service department
#Company: Alibaba Cloud Computing
#Version: 2.1
#########################################
check_os_release()
{
 while true
 do
 if cat /proc/version | grep redhat >/dev/null 2>&1
 then
 os_release=redhat
 echo "$os_release"
 break
 fi
 if cat /proc/version | grep centos >/dev/null 2>&1
 then
 os_release=centos
 echo "$os_release"
 break
 fi
 if cat /proc/version | grep ubuntu >/dev/null 2>&1
 then
 os_release=ubuntu
 echo "$os_release"
 break
 fi
 if cat /proc/version | grep -i debian >/dev/null 2>&1
 then
 os_release=debian
 echo "$os_release"
 break
 fi
 break
 done
}
check_memory_and_swap()
{
 mem_count=$(free -m|grep Mem|awk '{print $2}')
 swap_count=$(free -m|grep Swap|awk '{print $2}')
 if [ "$mem_count" -ge 15000 ] && [ "$mem_count" -le 32768 ]
 then
 if [ "$swap_count" -ge 8000 ]
 then
 echo -e "\033[1;40;31mYour swap is already enough.Do not need to add swap.Script will exit.\n\033[0m"
 rm -rf $LOCKfile
 exit 1
 elif [ "$swap_count" -ne 0 ]
 then
 echo -e "\033[40;32mYour swap is not enough,need to add swap.\n\033[40;37m"
 remove_old_swap
 create_swap 8192
 else
 echo -e "\033[40;32mYour swap is not enough,need to add swap.\n\033[40;37m"
 create_swap 8192
 fi
 elif [ "$mem_count" -ge 3900 ] && [ "$mem_count" -lt 15000 ]
 then
 if [ "$swap_count" -ge 3900 ]
 then
 echo -e "\033[1;40;31mYour swap is already enough.Do not need to add swap.Script will exit.\n\033[0m"
 rm -rf $LOCKfile
 exit 1
 elif [ "$swap_count" -ne 0 ]
 then
 echo -e "\033[40;32mYour swap is not enough,need to add swap.\n\033[40;37m"
 remove_old_swap
 create_swap 4096
 else
 echo -e "\033[40;32mYour swap is not enough,need to add swap.\n\033[40;37m"
 create_swap 4096
 fi
 else
 if [ "$swap_count" -ge 2000 ]
 then
 echo -e "\033[1;40;31mYour swap is already enough.Do not need to add swap.Script will exit.\n\033[0m"
 rm -rf $LOCKfile
 exit 1
 elif [ "$swap_count" -ne 0 ]
 then
 echo -e "\033[40;32mYour swap is not enough,need to add swap.\n\033[40;37m"
 remove_old_swap
 create_swap 2048
 else
 echo -e "\033[40;32mYour swap is not enough,need to add swap.\n\033[40;37m"
 create_swap 2048
 fi
 fi
}
create_swap()
{
 root_disk_size=$(df -m|grep -w "/"|awk '{print $4}')
 if [ "$1" -gt "$((root_disk_size-1024))" ]
 then
 echo -e "\033[1;40;31mThe root disk partition has no space for $1M swap file.Script will exit.\n\033[0m"
 rm -rf $LOCKfile
 exit 1
 fi
 if [ ! -e $swapfile ]
 then
 dd if=/dev/zero of=$swapfile bs=1M count=$1
 /sbin/mkswap $swapfile
 /sbin/swapon $swapfile
 /sbin/swapon -s
 echo -e "\033[40;32mStep 3.Add swap partition successful.\n\033[40;37m"
 else
 echo -e "\033[1;40;31mThe /var/swap_file already exists.Will exit.\n\033[0m"
 rm -rf $LOCKfile
 exit 1
 fi
}
remove_old_swap()
{
 old_swap_file=$(grep swap $fstab|grep -v "#"|awk '{print $1}')
 swapoff $old_swap_file
 cp -f $fstab ${fstab}_bak
 sed -i '/swap/d' $fstab
}
config_rhel_fstab()
{
 if ! grep $swapfile $fstab >/dev/null 2>&1
 then
 echo -e "\033[40;32mBegin to modify $fstab.\n\033[40;37m"
 echo "$swapfile swap swap defaults 0 0" >>$fstab
 else
 echo -e "\033[1;40;31m/etc/fstab is already configured.\n\033[0m"
 rm -rf $LOCKfile
 exit 1
 fi
}
config_debian_fstab()
{
 if ! grep $swapfile $fstab >/dev/null 2>&1
 then
 echo -e "\033[40;32mBegin to modify $fstab.\n\033[40;37m"
 echo "$swapfile none swap sw 0 0" >>$fstab
 else
 echo -e "\033[1;40;31m/etc/fstab is already configured.\n\033[0m"
 rm -rf $LOCKfile
 exit 1
 fi
}
##########start######################
#check lock file ,one time only let the script run one time
LOCKfile=/tmp/.$(basename $0)
if [ -f "$LOCKfile" ]
then
 echo -e "\033[1;40;31mThe script is already exist,please next time to run this script.\n\033[0m"
 exit
else
 echo -e "\033[40;32mStep 1.No lock file,begin to create lock file and continue.\n\033[40;37m"
 touch $LOCKfile
fi
#check user
if [ $(id -u) != "0" ]
then
 echo -e "\033[1;40;31mError: You must be root to run this script, please use root to install this script.\n\033[0m"
 rm -rf $LOCKfile
 exit 1
fi
os_release=$(check_os_release)
if [ "X$os_release" == "X" ]
then
 echo -e "\033[1;40;31mThe OS does not identify,So this script is not executede.\n\033[0m"
 rm -rf $LOCKfile
 exit 0
else
 echo -e "\033[40;32mStep 2.Check this OS type.\n\033[40;37m"
 echo -e "\033[40;32mThis OS is $os_release.\n\033[40;37m"
fi
swapfile=/var/swap_file
fstab=/etc/fstab
echo -e "\033[40;32mStep 3.Check the memory and swap.\n\033[40;37m"
check_memory_and_swap
echo -e "\033[40;32mStep 4.Begin to modify $fstab.\n\033[40;37m"
case "$os_release" in
redhat|centos)
 config_rhel_fstab
 ;;
ubuntu|debian)
 config_debian_fstab
 ;;
esac
free -m
echo -e "\033[40;32mAll the operations were completed.\n\033[40;37m"
rm -rf $LOCKfile